It has long been the practice in the burglar alarm art to attach electrically conductive foil strips around the margins of glass windows and glass doors. The foil strips are connected into an electric burglar alarm circuit. Then, if the window should be broken, the strip also breaks and causes an electric burglar alarm to be activated.
Self-adhesive terminal blocks have been provided in the prior art, which may be directly mounted on the glass, and which may be used to establish electrical connections to the foil strips. Such terminal blocks are usually formed with a base of an appropriate molded plastic material, and with a metal clamp and connector screw mounted on the base. The end of the foil strip is brought up a ramp on the base under the clamp, and the screw is threaded into the base through a hole in the end of the foil strip. The connecting wire is wrapped around the screw, and when the screw is tightened down into the base, it serves as a terminal for the wire, and also causes the clamp to hold the end of the foil strip firmly in place on the terminal block.
The prior art terminal blocks of the type described above are supplied as single blocks which may be used to establish electrical connection to a foil strip when the ends of the strip are brought off opposite ends of the glass, with one block being provided at each end. The prior art terminal blocks are also supplied as double blocks which may be used to establish electrical connections to a foil strip when both ends of the strip are brought off the same side of the glass.
In either case, the base of the single or double prior art blocks is adhesively attached to the glass at the edge of the window or door, with the metal clamping plate and screw removed. The end of the foil strip is then brought up over the edge of the base and up the sloped ramp on the base. The metal clamp is then replaced, and the screw is threaded through the plate and through the end of the foil strip into the base. The circuit wire, as mentioned above, is connected under the screw.
The terminal blocks of the present invention are advantageous in that they are constructed as detachable double blocks so that there is no need for the installer to purchase quantities of single and double blocks, as is the case in the prior art. Instead, the purchaser obtains only the double blocks of the invention, which he uses in the same applications as the double blocks of the prior art, and which he separates into single blocks only if and when the need arises.
The double blocks of the present invention are preferably sold as strips of a selected number of double blocks supported on a single adhesive strip to facilitate handling of the blocks. The installer merely selects a number of strips representing the terminal blocks required for any particular job. He then separates the double blocks from the strip as each is to be mounted in place, and separates the double blocks into single blocks if or when the requirement arises.
Another feature of the terminal block of the invention is that, in addition to being provided with a pressure-sensitive adhesive strip to permit the block to be mounted directly on the glass, the block is also provided with mounting holes to permit it to be mounted on the adjacent window or door frame, if so desired.
The base of the terminal block of the invention is formed of an appropriate molded plastic material, and is configured to define a channel across the top of the block to receive and guide the end of the foil strip in place over the top of the ramp, and which facilitates the operations required to attach the strip to the terminal block.